Following the Russo-Persian Wars of 1804–13 and 1826–28, the territories of the Iranian Qajar dynasty in the Caucasus were forcefully ceded to the Russian Empire and the Treaty of Gulistan in 1813 and the Treaty of Turkmenchay in 1828 finalized the borders between the Russian Empire and Qajar Iran. The areas to the north of the river Aras, including the territory of the contemporary Republic of Azerbaijan, were Iranian territory until they were occupied by Russia over the course of the 19th century. The Russo-Persian Wars of the 19th century settled the modern-day boundary of Iran, stripping it of all its Caucasian territories and incorporating them into the Russian Empire. The eventual formation of the Azerbaijan Democratic Republic in 1918 established the territory of modern Azerbaijan.

Azerbaijani language

Azerbaijani (/ˌæzərbaɪˈdʒɑːni/, /ˌɑː-/, /-ˈʒɑːni/) or Azeri (/æˈzɛəri/, /ɑːˈ-//əˈ-/), also referred to as Azerbaijani Turkish or Azeri Turkish ([ɑzærbɑjdʒɑn dili]), is a Turkic language spoken primarily by the Azerbaijani people, who are concentrated mainly in the South Caucasus geographical region. The language has official status in Azerbaijan and Dagestan (a federal subject of Russia), although in Iranian Azerbaijan, where the plurality of speakers live, it has no such status. The language is also spoken to lesser varying degrees in Georgia, Iraq, and Turkey.